1. Field of the Invention
The present invention relates generally to structures and vehicles having a compactable walkway and, more particularly, to folding stairs.
2. Description of the Related Art
Stairs and walkways enable access to locations and positions typically not otherwise accessible. However, use of such is typically limited to the scant moments of time it takes to achieve such access. Where access may already be achieved or may not be needed, such as when moving a structure and/or vehicle from one location to another location, stairs may serve only to be obtrusive, obstructive, unwieldy, and/or generally in the way. Accordingly, attempts have been made to provide stairs and walkways able to be compacted or otherwise reduced in size.
For example, U.S. Pat. No. 5,957,237 to Tigner discloses a collapsible step assembly that has upper and lower steps, and a housing which mounts below the door of a vehicle. The steps and housing are interconnected by pivotally mounted linkages. A pivot rod extends transversely through the housing with a linkage fastened to each end. A link arm is connected to the rod with a universal ball joint. The link arm is swivelly mounted to a drive gear with teeth which extend circumferentially along an arcuate edge portion. The drive gear is pivotally mounted to the housing and engages a drive gear extending from a motor. The drive gear rotates the pivot rod and, hence, the steps between retracted and extended positions. A flat outer edge of the drive gear abuts a mechanical stop in the extended position. When the user steps on the steps while they are extended, the stop will resist countertorque on the pivot rod from being applied through the gears to the motor. The geometry of the drivetrain causes the pivot point of the link arm to move past a central position to an overcenter position. In the overcenter position, a force on the link arm would tend to cause the drive gear to abut the stop so that the drive gear does not absorb any force.
Furthermore, U.S. Pat. No. 5,941,342 to Lee discloses a folding staircase comprises a plurality of step units each having a pair of horizontal link bars, a pair of vertical link bars that are pivotally coupled to corresponding the horizontal link bars, and a plate that are connected between the horizontal link bars, wherein the ends of the horizontal link bars are pivotally combined with those of the adjacent vertical link bars to form a step portion, and a fixing unit for fixing the step portion to a vehicle.
Still further, U.S. Pat. No. 5,111,906 to Abadia discloses a retractable ladder apparatus for access between a lower and an upper floor is provided. A ladder is moved by moving means, which may be a garage door opener, between a position of storage within the upper floor to a position where the lower end of the ladder abuts the lower floor.
However, in many cases, such devices fail to sufficiently retract, are unnecessarily complicated, include too many moving parts, are not adequately adapted for stairs along a side of a structure, and/or have a tendency to bind.
What is needed is a structure and/or vehicle including a folding stair and/or a folding stair set that solves one or more of the problems described herein and/or one or more problems that may come to the attention of one skilled in the art upon becoming familiar with this specification.